题目：

题解：

class Solution {
public:int subarraySum(vector<int>& nums, int k) {unordered_map<int, int> mp;mp[0] = 1;int count = 0, pre = 0;for (auto& x:nums) {pre += x;if (mp.find(pre - k) != mp.end()) {count += mp[pre - k];}mp[pre]++;}return count;}
};